Alternating-current motor.



V. A. FY-NN. 'ALTBRNATING CURRENT MOTOR. APPLICATION FILED MAY 8, 1909.

Patented Aug. 16, 1910.

Zzlre A. Fynn ,To all whom it may concern:

UNITED STATES PATENT OFFICE.

VALERE ALFRED FYNN, OF LONDON, ENGLAND.

ALTERNATING-CURRENI MOTOR.

Be it known that I, VALiJRE ALFRED FYNN, a sub ect of the King ofEngland, residing at London, England, have invented a certain new andusefulAlternating-Current Motor,

ofwhich the following is a such a full, clear,

and exact description as will enable any one skilledin the art to whichit appertains to make and use the same, reference being had to theaccompanying drawings, forming part of this specification.

My invention-relates to that type of alternate currentmotor whichcarries onits in-- duced member an outer commutedwinding and an innerwinding c-losedon itself, the former being situated in slots placed nearthe air-gap .-the latter being disposed in other slots separated fromthe outer slots by a certain amount of magnetic material. The saidmotors are "mostly built for use on singlephase circuits. As long as themotor speed is considerably below synchronisn'i the winding closedjonitself takes a heavy lagging current which is ofcojurse reflected inthe primary and which lowers the'etliciency and power factor ofthemctor. At synchrohism the operation of the motor only depends on thecommuted winding and much of the rotor copper is idle. Above synchronismthe winding. closed on itself opposes the action of the commuted windingand reduces the efficiency without being able to sufliciently andpositively limit the speed of the machine owing to the magnetic pathwayor shunt existingbetween the inner and outer slots intherotor. Atall-speeds the current .required by the commuted winding for theproduction of a suitable motor field is i11 creased by the presence ofthe winding closed on itself. The result of all this is that themotor=speed is not constantand that the actions of the two rotorwindings are antago- Broadly speaking I: achieve my objects by providingmeans whereby, after 'a certain Specification of Letters Patent.

Application filed May a, 1909. Serial No. 494,905.

Patented Aug. 16, 1910.

REISSUED speed has been reached, the tendency of the commuted winding togive the motor a series characteristic is destroyed and converted into atendency to give ita shunt characteristic with a normal working speedclosely approximating to the synchronous. I can still further improvethese machines by combining therewith one of the two phase-compensatingdevices disclosed by me in my .Patent No. 777,198, and which consists inincluding in the"exciting circuit of the com- ;muted winding an E. M. F.practically in phase with that of the supply.

In the accompanying diagrammatic drawings, which show several two-poleembodiments of my invention, Figure 1 is a motor of the said typeadapted to be started as a' series conduction or induction machine, Fig.2 is a motor adapted to be started as a shunt conduction machine, andFig. 3is a machine adapted to be started'as a series induction motor.Fig. a shows the position of the windings in the rotor.

Referring to Fig. l which discloses the starting connections in one formof my improved motor,- the main stator inducing winding 12 is connectedin series relation with the commuted winding 14 by way of the brushes15, 16 and across the mains 10, 11. Therotor winding closed on itself isshown at 13 and is by way of example supposed to be of the squirrel-cagetype. The machine starts something like a series conduction motor,although not entirely so, owing to the presence of 13, and the commutedwinding generally tends to raise the Speed beyond the synchronous. Assoon as I a sufficient speed has been reached I close switches 23 and25. As soon as this is done the commuted wind-mg tends to give themachine a shunt instead of a serles characteristic thus eliminating allantago-' of the brushes 15, 16 is closed over a compensating winding 24here disposed on the stator, this arrangement increases the power factorof the motor and also improves its general operation. .This compensatingE. M. F. can be derived from any convenient source and need not be takenfrom a motor winding as shown in Fig. 1. In a modification I coulddirectly short-circuit the brushes 15,16 after a .sufiiciant speedhasbeen reached, thus securing all the 'advantages I have enumerated exceptthose contingent on the use of a compensating E. M. $01116short-circuited at starting-thus simplifying the switching operations.When up to speed the commuted winding is closed along another axis withor without the inclusion,

of a compensatin -E. M. F. In order to reverse the directlon ofrotationin either of the cases just described it is necessary either toreverse the current through 12 or through 14 adjusting the compensatingfea ture to suit.

Fig. 2 shows a machine which starts something like a "shunt conductionmotor, although not entirely so owing to the presence of 13. Thecommuted winding may, tend to drive the motor-beyond synchronism or keepit below that speed according to the proportions chosen. The switchesare shown in the starting position, 12'is directly connected to themains 10, 11 and an E. M. F.

of about thesame phase as that of the supply is impressed on thecommuted winding 14 by way of the brushes 15, 16 and in parallel with12. The E. M. F. impressed on .14 is by wayof example derived from 12itself at point 26. When the motor has reached a suflicient speed switch23 is closed and switch 25 moved on to point 27 or 28. Point 27 may beso chosen as to derive from 12 the desired compensating F. If 25 standson 28 then the compensating feature is cut out, but the improved motorstill retains the other advantages I have previously enumerated. Inorder to reverse the direction of rotation it is necessary either toreverse the current through 1201 through 14 adjusting the compensatingfeature to suit.

Fig. 3 shows a machine which starts something like a series inductionmotor although not entirely so owing to the presence of 13. The-commutedwinding generally tends to drive the motor beyond its synchronous speed.The switches are allshown open and 12 alone is directly connected to themains 1O, 11. Inorder to start the motor say ina clockwise directionswitches 30 and 32 are closed together with switchv 33. If the motor isto be started in the opposite direction then switches 29, 31 and 33 mustbe closed. Instead of closing 33 it'is also possible at starting toclose the reversing switch 34 in the one or the other direction, andaccording to this direction the starting torque will be either increasedor decreased by the inclusion of 24 in the brush circuit. Supposingswitches 30, 32 and 33 have beencclosed at starting't'h'en as sdon asthe motor has reached a sufficient speed switches 29 and 31 must also beclosed tion.

thus eliminating all antagonistic actions from the motor. If it bedesired to compensate the machine then switch 33 must be opened and 34closed in the correct direc- Having fully described my invention, what Iclaim as new and desire to secure by Letters Patent of the United Statesis:

1. In an alternating current motor the combination with a statorprovided with a main inducing winding, of a rotor provided with acommuted winding and a second winding closed on itself, a magnetic shuntforming a pathway for ma with saidcommuted windmg without linking withsaid second winding, and means for directing the flow of current in saidcommuted winding along two axes.

2. In an alternating current motor, the

combination with a stator provided with a' main inducing winding, of arotor provided with a commuted winding and a second winding closed onitself, said second winding being embedded in the rotor core andseparated from the commuted winding by sufiicient magnetic material toform a pathway for magnetic flux to pass through said commuted windingwithout penetrating said second winding, said commuted winding beingclosed by way of brushes along two axes.

3. In an alternating current -motor, the combination with a statorprovided with a main inducing winding, of a rotor provided with acommuted winding and a second windingclosed on itself, said secondwinding being embedded in the rotor core and separated from thecommuted. winding by sufiicient magnetic material to form a pathway formagnetic flux to pass through said commuted winding without penetratingsaid second winding, said commuted winding being closed by way pfbrushes along two axes, one of which approximately coincides with theaxis of the main inducing winding.

4. In an alternating current motor, the combination with a statorprovided with a main inducing winding, of a rotor provided with acommuted winding-and a second short-circuited along one axis, and meansfor impressing a compensating E. M; F. on said commuted winding alonganother axis.

5. In an alternatingcurrent motor, the combination with a statorprovided with a main inducing winding, of a rotor provided with acommuted winding and a second winding closed onitself, saidsecondwinding being embedded in the rotor coreand separated from the commutedwinding by sufficient magnetic material to form a path- "I In testimonywhereof I have hereunto set} way for magnetic flux tov pass through saidcommuted winding without penetrating said second winding, and means forclosing the circuit of said commuted Winding along two axesdwhen themotor has reached any desired snee of the two subscribing Witnesses.

VALERE ALFRED FYNN. [1 8.]

Witnesses: Y

W. S. THOMAS, H. H. TWINGLEY.

my hand and afiixed my seal in the presence

